Try this: http://annibyniaeth.com/2019/03/29/firefly-iii-on-unraid-letsencrypt/
Resurrected the blog for you
For those that just want a config file, it is below:
server {
listen 443 ssl;
include /config/nginx/ssl.conf;
client_max_body_size 0;
server_name subdomain.doman.tld;
location / {
add_header X-Forwarded-Proto "https";
proxy_set_header Host $host;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_pass http://[SERVERIP]:[PORT FOR FIREFLY];
}
}
Nginx configs are not my thing, so do let me know if I've got something egregiously wrong!